In recent years, in the welding industry, it is greatly demanded to increase a welding speed or to reduce sputtering in order to enhance productivity. In order to meet these demands, an arc welding apparatus of a consumable electrode type is developed and an arc welding control method is devised. However, there is not devised an arc welding control method of reducing an energy input of welding so as not to cause burn-through or the like due to welding of a thin plate.
FIG. 4 is a chart showing an output waveform in a conventional arc welding control method accompanied by a short circuit, illustrating a time variation in a wire feeding speed Wf and a welding current Aw. Referring to an arc welding control method of alternately generating a short circuit state and an arc state to carry out welding while feeding a welding wire to be a consumable electrode, a wire feeding motor is controlled to cause the wire feeding speed Wf to cyclically repeat forward feeding and backward feeding. It is known that control is carried out to reduce a welding output for a period having a small wire feeding amount and to increase the welding output for a period having a large wire feeding amount with the control of the wire feeding motor as shown in FIG. 4 (for example, see Patent Literature 1).
Referring to the wire feeding speed Wf, moreover, each of the forward feeding and the backward feeding is carried out once in one cycle so that each of the generation of the short circuit and opening of the short circuit (the generation of an arc) is once performed correspondingly. Thus, the welding control is accompanied by an arc phenomenon depending on the cyclic operation of the wire feeding speed. An inverse number of a cycle of a preset wire feeding speed serves as a short circuit frequency so that stable welding having a certain short circuit frequency can be carried out.
Referring to the conventional arc welding control method, for example, stable welding can be carried out without burn-through in the case in which a plate having a thickness of 0.8 mm or more is to be welded. However, in the case in which a thin plate having a thickness of 0.6 mm or less is to be welded, for example, an energy input amount to a base metal is large so that the burn-through occurs. For this reason, there is a problem in that satisfactory welding cannot be carried out.